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SubjectRe: [PATCH 2/3] dmaengine: at_xdmac: enhance channel errors handling in tasklet
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Vinod,

Thanks for your review, I'm preparing v2.

On 11/02/2019 at 12:58, Vinod Koul wrote:
> On 05-02-19, 12:03, Nicolas Ferre wrote:
>> Complement the identification of errors with stoping the channel and
>> dumping the descriptor that led to the error case.
>>
>> Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
>> ---
>> drivers/dma/at_xdmac.c | 43 ++++++++++++++++++++++++++++++++++++------
>> 1 file changed, 37 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
>> index 37a269420435..ec7a29d8e448 100644
>> --- a/drivers/dma/at_xdmac.c
>> +++ b/drivers/dma/at_xdmac.c
>> @@ -1575,6 +1575,41 @@ static void at_xdmac_handle_cyclic(struct at_xdmac_chan *atchan)
>> dmaengine_desc_get_callback_invoke(txd, NULL);
>> }
>>
>> +static void at_xdmac_handle_error(struct at_xdmac_chan *atchan)
>> +{
>> + struct at_xdmac *atxdmac = to_at_xdmac(atchan->chan.device);
>> + struct at_xdmac_desc *bad_desc;
>> +
>> + /*
>> + * The descriptor currently at the head of the active list is
>> + * broked. Since we don't have any way to report errors, we'll
>
> You meant borked or broken...

Broken

>
>> + * just have to scream loudly and try to carry on.
>
> should we carry on or abort..?

Changed in:

* just have to scream loudly and try to continue with other
* descriptors queued (if any).

>> + */
>> + if (atchan->irq_status & AT_XDMAC_CIS_RBEIS)
>> + dev_err(chan2dev(&atchan->chan), "read bus error!!!");
>> + if (atchan->irq_status & AT_XDMAC_CIS_WBEIS)
>> + dev_err(chan2dev(&atchan->chan), "write bus error!!!");
>> + if (atchan->irq_status & AT_XDMAC_CIS_ROIS)
>> + dev_err(chan2dev(&atchan->chan), "request overflow error!!!");
>> +
>> + spin_lock_bh(&atchan->lock);
>> + /* Channel must be disabled first as it's not done automatically */
>> + at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask);
>> + while (at_xdmac_read(atxdmac, AT_XDMAC_GS) & atchan->mask)
>> + cpu_relax();
>> + bad_desc = list_first_entry(&atchan->xfers_list,
>> + struct at_xdmac_desc,
>> + xfer_node);
>> + spin_unlock_bh(&atchan->lock);
>> + /* Print bad descriptor's details if needed */
>
> Well this is not great to look and read at, please do consider adding
> empty line before comments or logical blocks..

True, indeed.

>> + dev_dbg(chan2dev(&atchan->chan),
>> + "%s: lld: mbr_sa=%pad, mbr_da=%pad, mbr_ubc=0x%08x\n",
>> + __func__, &bad_desc->lld.mbr_sa, &bad_desc->lld.mbr_da,
>> + bad_desc->lld.mbr_ubc);
>
> not dev_err?

Well, we have the dev_err at the beginning of the function, I think it's
enough: this is really debugging information that needs to be activated
to track the DMA configuration bug: it's not meant for production.

>> +
>> + /* Then continue with usual descriptor management */
>> +}
>> +
>> static void at_xdmac_tasklet(unsigned long data)
>> {
>> struct at_xdmac_chan *atchan = (struct at_xdmac_chan *)data;
>> @@ -1594,12 +1629,8 @@ static void at_xdmac_tasklet(unsigned long data)
>> || (atchan->irq_status & error_mask)) {
>> struct dma_async_tx_descriptor *txd;
>>
>> - if (atchan->irq_status & AT_XDMAC_CIS_RBEIS)
>> - dev_err(chan2dev(&atchan->chan), "read bus error!!!");
>> - if (atchan->irq_status & AT_XDMAC_CIS_WBEIS)
>> - dev_err(chan2dev(&atchan->chan), "write bus error!!!");
>> - if (atchan->irq_status & AT_XDMAC_CIS_ROIS)
>> - dev_err(chan2dev(&atchan->chan), "request overflow error!!!");
>> + if (atchan->irq_status & error_mask)
>> + at_xdmac_handle_error(atchan);
>>
>> spin_lock(&atchan->lock);
>> desc = list_first_entry(&atchan->xfers_list,
>> --
>> 2.17.1
>


--
Nicolas Ferre
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